In bronchial asthma and bronchomalacia, which are representative examples of respiratory system diseases, the luminal sectional area of bronchial tubes is reduced, to cause such a symptom as respiratory difficulty (dyspnea). Exemplary methods for treatment of the bronchial asthma and the like include the usage of a drug for dilating the bronchial tubes (bronchodilator) and a method of placing a stent to indwell in the bronchial tube.
In the conventional method of treatment, however, it is necessary to preliminarily measure the diameter of the lumen by use of a diagnostic imaging apparatus such as CT or an endoscope. Even if the inside diameter of the lumen could be measured, the outside diameters of commonly available stents are determined at the time of manufacture of the stents, from which a suitable one has to be chosen. Thus, it cannot be said that a stent suited to the patient's bronchial tube can always be provided.
A catheter by which the diameter of a stenosed part of a living body lumen can be freely expanded and contracted is disclosed, for example, in Patent Document 1. Specifically, Patent Document 1 discloses a technology wherein the diameter of a body lumen dilating spiral body disposed forwardly of a distal portion of a main body of a body lumen dilating catheter is freely expandable or contractible by a rotational force transmission member.